Flexible device for transferring heat by circulating a two-phase fluid

Abstract

The invention relates to a two-phase heat transfer device (1) capable of operating in a space environment, the device comprising: - a cavity (10) containing a two-phase fluid in the liquid-vapour equilibrium state; - a flexible portion (30) and two interface parts (40), one of the interface parts, the flexible portion and the other interface part being successively connected to one another, the device being characterised in that the flexible portion comprises a sealed flexible sheath (31) inside which at least one flexible internal liquid circulation duct (32) extends, which duct is surrounded by a space (33) for circulating the vapour.

Description

technical field

[0001] This disclosure relates to a flexible two-phase fluid circulation heat transfer device for use in space environments. Previous technique

[0002] Patent IN-2020 / 21025032 describes a heat transfer device with a flexible section. However, this technical solution requires a specific end-to-end design for the heat transfer device and does not allow for the reuse of existing evaporators or condensers found in standard solutions, which generally have a fixed geometry, used in the space sector. Furthermore, the materials used must be compatible with space applications.

[0003] We also know of US patent 2008 / 099186, which describes a flexible adiabatic duct connected via interfaces to an evaporator and a condenser. However, the structures of the interfaces, the evaporator, and the condenser are not described. The dimensions of the flexible adiabatic duct also appear to be sensitive to its positioning, which generally reduces performance. Furthermore, the materials used must also be suitable for use in the space sector. Summary

[0004] This disclosure improves the situation. In particular, one aim of the invention is to provide a heat transfer device suitable for use in a space environment, which is flexible, thermally efficient, and relatively inexpensive to manufacture.

[0005] In this regard, a two-phase heat transfer device is described according to claim 1.

[0006] In some embodiments, said internal flexible liquid circulation conduit surrounded by a space for vapor circulation is free with respect to the flexible sheath.

[0007] According to the invention, the assembly formed by the flexible portion attached to the two interface pieces is connected, on both sides, to two rigid heat pipes belonging to the two-phase heat transfer device.

[0008] In some embodiments, the capillary diameter of the rigid heat pipe capillary medium is smaller than the capillary diameter of the annular portion of each interface piece, which is itself smaller than or equal to the diameter of the flexible internal liquid circulation channel. In some embodiments, the device further comprises at least one hollow rod having a first threaded end that screws against the liquid circulation channel of each interface piece and another end that is inserted into said flexible internal channel. In some embodiments, each interface piece is a single-piece metal component manufactured by additive manufacturing.

[0009] In some embodiments, each interface part is made of aluminum or aluminum alloy, as are the rigid heat pipes made of aluminum or aluminum alloy or stainless steel.

[0010] In some embodiments, each rigid heat pipe comprises a first sheath extending over a part of one of the interface pieces, and the sheath of the flexible portion extending over a part of this interface piece, the first and second sheaths being clamped by a clamping piece against this interface piece.

[0011] In some embodiments, the first sheath butts up against a collar of the interface piece, the second sheath partially covering this collar.

[0012] According to another object, a method according to claim 9 is proposed.

[0013] A key advantage of the invention lies in the fact that the use of one or more flexible channels makes the heat transfer device flexible. Furthermore, the flexible section is easier to manufacture because its vapor conduits are not directly attached to the outer flexible duct, allowing for different configurations depending on the application requirements. The cost of manufacturing the intermediate flexible section is also reduced.

[0014] Another advantage of the invention is that it can be easily adapted for existing evaporators and condensers. It is simply a matter of sizing the interface parts and the liquid channel sections accordingly.

[0015] Advantageously, the assembly according to the invention ensures a progressively increasing capillary diameter through a simple and easy-to-implement design. Specifically, tightening the screw fully allows for a clearance smaller than the capillary diameter, and the elastic insertion into the liquid channel may result in a negligible capillary diameter deformation. The flange also facilitates a reliable and simplified assembly process. The increasing capillary diameter towards the flexible channels also allows them to have a relatively large internal diameter, on the order of a millimeter, which helps to minimize pressure losses.

[0016] Another advantage is that the interface piece can be easily made of aluminum or stainless steel using an ALM-type manufacturing process. Brief description of the drawings

[0017] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which: Fig. 1 [ Fig. 1 ] schematically represents the operation of a two-phase heat transfer device according to one embodiment. Fig. 2a [ Fig. 2a ] represents an example of an interface component. Fig. 2b [ Fig. 2b ] represents a longitudinal section of an example of an interface part. Fig. 3 [ Fig. 3 [ ] represents an example of a rod for assembling a flexible hose to an interface part Fig. 4 [ Fig. 4 ] schematically represents a partial view of a two-phase heat transfer device according to one embodiment. Fig. 5a; Fig. 5b ; Fig. 5c; Fig. 5d [ Fig. 5a] ; [Fig. 5b ] ; ] Fig. 5c] ; [Fig. 5d ] schematically represent the main steps of an assembly process for a two-phase heat transfer device. Description of the implementation methods

[0018] Reference is now being made to the figure 1Figure 1 schematically represents a two-phase heat transfer device suitable for operation in a space environment. Two heat exchange portions, one for vaporization and the other for condensation, are connected by this two-phase heat transfer device. The device comprises a sealed cavity containing a saturated two-phase fluid in liquid-vapor equilibrium, i.e., comprising a vapor phase and a liquid phase. One part of the device is in thermal contact with a so-called hot source, for example, equipment to be cooled, and another part is in thermal contact with a so-called cold source, for example, space.The two-phase fluid circulates within the cavity, the liquid part of the fluid evaporating in the vicinity of the heat source, the resulting vapor moving towards the cold source where it is condensed, and where it thus returns the stored thermal energy to the cold source.

[0019] To allow the circulation of the liquid phase within the cavity, the cavity includes a liquid circulation circuit designed to permit capillary flow. The cavity also includes a vapor circulation circuit comprising one or more vapor circulation channels. The liquid and vapor circuits are in fluid communication to allow the circulation of the two-phase fluid and its phase changes.

[0020] The heat transfer fluid contained in the cavity can, for example, be water, ammonia, methane, ethane, propylene, methanol or ethanol in a liquid-gas equilibrium state.

[0021] The device 1 comprises, for example, at least two heat exchange portions: a vaporization portion, in thermal contact with the hot source, and a condensation portion, in thermal contact with the cold source. The heat exchange portions are connected by a liquid circuit and a vapor circuit of the transfer device 1. The transfer device 1 comprises rigid heat pipes. Each of these rigid heat pipes comprises, for example, a capillary medium 21 for liquid circulation, this capillary medium forming part of the cavity's liquid circuit, and at least one vapor circulation groove 22, forming part of the cavity's vapor circulation circuit. For example, each rigid heat pipe may comprise a central groove 22 surrounded by the capillary medium 21.Rigid heat pipes 20 are made of a thermally conductive material, for example metal, for example aluminium or aluminium alloy, or stainless steel.

[0022] In this respect, the device 1 comprises a flexible section 30 and two interface pieces 40, each interface piece being shaped to provide a mechanical and fluidic interface between the flexible section and each rigid heat pipe. The two rigid heat pipes 20 are thus connected to each other successively by an interface piece 40, the flexible section 30, and another interface piece 40.

[0023] The flexible portion 30 comprises a leak-proof flexible sheath 31 within which extends at least one internal flexible liquid circulation conduit 32, surrounded by a space 33 for vapor circulation. The flexible liquid circulation conduit(s) are flexible leak-proof conduits, made, for example, of PTFE. The flexible sheath 31 may, for example, be a braided metal sheath. Alternatively, the sheath may be made of corrugated metal. According to another embodiment, the flexible sheath 31 may comprise an internal corrugated metal sheath surrounded by an external braided metal sheath. The metal used may, for example, be stainless steel.

[0024] With reference to figures 2a and 2b, each interface piece 40 includes at least one liquid circulation channel 41 intended to be in liquid communication with a flexible internal conduit 32 once the assembly of the device 1 has been completed, each liquid circulation channel 41 being extended by a capillary portion 42 enabling the interface with the capillary medium 21 of a rigid heat pipe 20 to be made. Each interface piece thus ensures the continuity of the liquid circuit.

[0025] Each interface piece 40 further includes an internal steam circulation conduit 43 which, once the device is assembled, is in fluidic communication with the steam circulation groove 22 of a rigid heat pipe 20 and with the steam circulation space 33 of the flexible portion 30 so as to ensure continuity of the steam circulation circuit.

[0026] In some embodiments, the flexible portion 30 comprises several internal flexible liquid circulation conduits 32, and each interface piece comprises as many liquid circulation channels 41. Each internal flexible liquid circulation conduit 32, surrounded by a space for vapor circulation 33, is free with respect to the sheath. That is, the liquid circulation channels are not directly connected to the sheath. The liquid circulation channels can be distributed at constant angular intervals around the circumference of the internal vapor circulation conduit 43. In the example shown in the figure 2a , each interface piece includes three liquid circulation channels 41 and the flexible portion includes three conduits 42.

[0027] With reference to the figure 2bFigure 40, which represents a longitudinal cross-sectional view of an interface component 40, shows that the component 40 comprises two consecutive sections. The first section comprises one or more liquid circulation channels 41 and a section of the internal vapor circulation conduit 43, and the second section comprises a circumferential capillary portion 42 extending around a section of the internal vapor circulation conduit 43. In some embodiments, the characteristic capillary dimension of the liquid circuit extending from the flexible portion 30 to a rigid heat pipe 20 increases from the rigid heat pipe 20 to the flexible portion 30. The characteristic capillary dimension may correspond, for lattice-type capillary media, to the diameter of the largest spherical particle that can pass through it, and, for groove-type capillary media or for tubes, to the hydraulic diameter of a groove or tube.Thus, the capillary dimension of the capillary medium 21 of the rigid heat pipe is less than or equal to the capillary dimension of the capillary portion 42 of an interface piece, which is itself less than or equal to the diameter of the internal channel 41 of an interface piece, which is itself less than or equal to the diameter of a flexible conduit 32 of the flexible portion 30. According to a non-limiting example, the capillary dimension of the capillary medium 21 may be less than 1 mm, for example between 0.5 and 1 mm, and the internal diameter of a flexible conduit 32 may be between 1 and 2 mm, for example equal to 1.5 mm.

[0028] Each interface part 40 can be a single-piece metal component manufactured using additive manufacturing. It can be made of aluminum, aluminum alloy, or stainless steel.

[0029] In cases where one of the interface pieces 40 and the rigid heat pipe 20 is made of stainless steel and the other piece is made of aluminum or aluminum alloy, the aluminum or aluminum alloy piece can advantageously be coated to prevent direct contact between the stainless steel and the aluminum, which could lead to galvanic corrosion. This coating could, for example, but not limited to, be PTFE or an alumina deposit.

[0030] With reference to Figures 1 , 3 and 4For assembling the flexible portion 30 to the interface parts 40, the device 1 further comprises rods 50, each having a first end 51 with an external thread, for being screwed into the liquid circulation channel 41 of an interface part, said channel also having a thread at its end, and a second end 52 shaped to be fitted into one end of a flexible conduit 32. Each rod is hollow, i.e., it comprises an internal channel opening at both ends, so that the liquid contained in the flexible conduit 32 can flow to the channel 41 of an interface part by passing through the inside of a rod 50. Back to the figure 2bEach liquid circulation channel 41 includes a threaded end section 410, this section having a diameter larger than the diameter of the rest of the channel. The channel thus forms a shoulder 411 against which the rod 50 can be screwed as a butt, so as to ensure good capillary continuity. The diameter of the rest of the channel, that is, the portion of the channel 41 extending between the shoulder and the capillary portion 42, can correspond to the internal diameter of the rod 50. More generally, the internal diameter of the rods 50 is between the internal diameter of the liquid circulation channel 41 of an interface piece and the internal diameter of the flexible conduit 32.

[0031] Each rigid heat pipe 20 further includes a sheath 23 extended relative to the capillary medium 21, enabling it to receive one end of an interface piece 40, in particular one end of the section of the interface piece comprising the capillary portion 42, so that once the interface piece is assembled to the rigid heat pipe, the sheath 23 surrounds an end section of the interface piece.

[0032] Furthermore, the flexible sheath 31 of the flexible portion is also longer than the flexible pipes 32 located inside so as to be able to receive one end of an interface portion, in particular the end of the interface piece comprising the internal channel 41, so that once the interface piece is assembled to the flexible portion, the sheath 31 surrounds an end section of the interface piece.

[0033] With reference to the figure 4The device 1 further includes a clamping piece 60 that clamps the sheath 23 of a respective rigid heat pipe and the flexible sheath 31 of the flexible portion to a respective interface piece 40. This clamping piece 60 may, for example, be a sleeve that clamps the interface piece 40 and the ends of the two sheaths 23, 31 extending around the interface piece. In some embodiments, the sleeve 60 is a heat-shrinkable shape-memory sleeve that shrinks upon exposure to cold or heat, depending on the sleeve design.

[0034] In some embodiments, each interface piece may further include a shim collar 44 ( Fig. 4) extending over the external surface of the part 40, this collar 44 forming a stop for the sheath 23 of the rigid heat pipe, and being at least partially covered by the flexible sheath 31 of the flexible portion 30. In one embodiment, each interface part 40 includes on its external surface a circumferential groove 45 and the collar 44 is formed of two C-shaped parts that can be inserted into the groove 45.

[0035] With reference to figures 5a to 5c We will now describe an example of an assembly process for the heat transfer device 1 described above.

[0036] The process includes a first step 100 of assembling a flexible portion 30 to each interface piece 40. In some embodiments, this step includes, with reference to the figure 5a , for each interface piece, the assembly of a rod 50 by screwing the threaded end to the interface piece 40 and, with reference to the figure 5b, the insertion of the other end into the end of a flexible pipe 32, then the insertion of the assembly into the flexible sheath 31 of the flexible portion, so that the flexible pipe(s) 32 are fully contained within the sheath and the sheath also covers an end part of each interface piece 40.

[0037] The process also includes, with reference to the figure 5c A step 200 involves assembling each interface piece 40 to a respective rigid heat pipe by at least partially inserting the capillary portion 42 of each interface piece into the sheath 23 of the rigid heat pipe. Prior to this step, the method may also include positioning a collar 44 on the external surface of each interface piece to form a stop for the sheath 23.

[0038] In some embodiments, the process also includes, with reference to the figure 5d, a step 300 of tightening the assembly of each interface piece 40 with the flexible portion and each rigid heat pipe. This tightening is advantageously achieved by means of the heat-shrinkable sleeve 60, which can be positioned around a rigid heat pipe 20 and then slid until it is superimposed on an interface piece 40 before being thermally shrunk to tighten together the ends of the two sheaths 23, 31 and the interface piece 40.

[0039] Alternatively, the 300 clamping by a sleeve can be replaced by a definitive assembly of each interface piece to the flexible portion and a rigid heat pipe for example by welding or brazing.

[0040] In one embodiment, where clamping is achieved using a heat-shrink sleeve, each sleeve can be positioned prior to step 200, i.e., after the collar 44 has been assembled to the interface, then the rods 50 to the interface piece 40 have been assembled, and finally the flexible portion 30 to the interface piece has been assembled 100. The capillary portion 42 of each interface piece can then be inserted into the sheath 23 of the respective rigid heat pipe before the sleeve shrinks to clamp the interface piece 40 to the flexible portion 30 and the rigid heat pipe 20.

[0041] The two-phase heat transfer device 1 described above exhibits flexibility thanks to its flexible section. By adjusting the length of this section to accommodate the bending radius of the sheath 31, significant bending angles can be achieved, up to 90° or even 180°. Furthermore, the device 1 is robust due to the connections between its various components, ensuring efficient and functional heat exchange even at large bending angles.

[0042] This device can advantageously be used in a spacecraft comprising deployable appendages, where a rigid heat pipe 20 is mounted on a deployable appendage and another rigid heat pipe 20 is mounted on the body of the spacecraft.

[0043] In another application, this device can be used to provide a thermal link between an instrument mounted on the body of a spacecraft via an isostatic platform, for example a sensor or an observation instrument, and the body of a spacecraft, in order to cool the instrument without transmitting mechanical stresses or vibrations that could disturb its adjustment.

[0044] This device can also be used to ensure heat exchange between two walls forming an angle between them, for example two walls at 90°C; the flexibility conferred by the flexible portion makes it possible to reduce the precision constraints on the alignment of the walls and thus simplify the assembly.

[0045] List of digital references: 1: Heat transfer device 10: Internal cavity 20: Rigid heat pipe 21: Capillary medium 22: Vapor circulation groove 23: Sheath 30: Flexible section 31: Flexible sheath 32: Internal liquid circulation duct 33: Vapor circulation space 40: Interface piece 41: Liquid circulation channel 411: Shoulder 42: Capillary section 43: Internal vapor circulation duct 44: Collar 45: Circumferential groove 50: Hollow rod 51: Threaded end 52: Second end 60: Sleeve 100: Assembly of a flexible section to an interface piece 200: Assembly of an interface piece to a rigid heat pipe 300: Clamping

Claims

1. A two-phase heat transfer device (1) capable of operating in a space environment, adapted to connect together two respectively vaporisation and condensation heat exchange portions, the heat transfer device comprising: - a vapour circuit on the one hand and a liquid circuit on the other hand, - two rigid heat pipes (20), each comprising a capillary medium (21) forming part of the liquid circuit, and at least one vapour circulation groove (22) forming part of the vapour circuit, - at least one flexible portion (30) and two interface parts (40), the two rigid heat pipes (20) being connected together successively by one of the interface parts (40), the flexible portion (30) and the other interface part (40), wherein the flexible portion (30) comprises a sealed flexible sheath (31) inside which at least one liquid circulation flexible inner conduit (32) extends, surrounded by a vapour circulation space (33), characterised in that said liquid circulation flexible inner conduit (32) is sealed and flexible, each interface part (40) comprising at least one liquid circulation channel (41) in liquid communication with said flexible inner conduit (32) on the one hand and extending to an annular portion (42) on the other hand, this annular portion (42) having a determined capillarity and abutting against the capillary medium (21) forming the liquid circuit of a rigid heat pipe (20).

2. The device (1) according to claim 1, further comprising at least one hollow rod (50) having a first threaded end (51) screwed abutting against the liquid circulation channel (41) of each interface part (40) and another end (52) sleeved into said flexible inner conduit (32).

3. The device (1) according to any one of the preceding claims, wherein said liquid circulation flexible inner conduit (32) surrounded by a vapour circulation space (33) is free relative to the flexible sheath.

4. The device (1) according to one of the preceding claims, wherein the capillary diameter of the capillary medium of each rigid heat pipe is less than the capillary diameter of the annular portion (42) of each interface part (40), itself less than the diameter of the liquid circulation flexible inner conduit (32).

5. The device (1) according to one of the preceding claims, wherein each interface part (40) is made of aluminium or aluminium alloy, similarly the rigid heat pipes (20) are made of aluminium or aluminium alloy or stainless steel.

6. The device (1) according to the preceding claim, wherein each interface part (40) is a one-piece metal part manufactured by additive manufacturing.

7. The device (1) according to one of the preceding claims, wherein each rigid heat pipe (20) comprises a first sheath (23) extending over a part of one of the interface parts (40), and the sheath (31) of the flexible portion (30) extending over part of this interface part (40), the first and second sheaths (23, 31) being clamped by a clamping part (60) against this interface part (40).

8. The device (1) according to the preceding claim, wherein the first sheath (23) abuts against a flange (44) of the interface part (40), the second sheath (31) partially covering this flange.

9. A method for assembling a device (1) according to any one of the preceding claims, comprising: - assembling (100) a flexible portion (30) to an interface part (40), and then - assembling (200) the interface part (40) to a rigid heat pipe (20), and - clamping (300) the assembly of the interface part (40) with the flexible portion (30) and the rigid heat pipe (20), clamping (300) being carried out by a heat-shrinkable sleeve (60) previously slid around the rigid heat pipe (20) and then slid around the interface part (40).

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